African Mapping Highlights Risk Of Drought and Flood

African Mapping Highlights Drought and Flood

African mapping highlights risk of drought and flood
The map will help predict droughts Nell Barrie
27 July 2007
Source: SciDev.Net

The European Space Agency (ESA) has produced maps of soil moisture levels in southern Africa, and says they will help predict floods and droughts.

The maps of countries in the Southern African Development Community were published online last week (16 July) and will be available to governmental and independent organisations free of charge.

Conventional methods of measuring soil moisture are expensive and inaccurate as each measurement has to be done on-site. ESA's ENVISAT satellite measures soil moisture levels by emitting radar waves and measuring the energy bounced back by the soil.

High levels of soil moisture can lead to flooding and erosion, and low levels cause crops to wilt and die.

Annett Bartsch, project coordinator at Vienna University of Technology, Austria, explained how the maps are used. "Areas of saturated upper soil can be identified with ENVISAT," she said. These areas are those at risk of flooding.

The maps can also help predict droughts by looking at past trends in soil moisture. "Provided that a long enough reference database is available, anomalies can be identified and thus… drought risk areas identified," she told SciDev.Net.

In a changing climate, predicting when and where floods are likely to happen is becoming more and more important, according to Geoff Pegram, co-researcher on the project at the University of KwaZulu-Natal in South Africa. "Although we cannot prevent floods, we can anticipate them and hopefully get people out of the way."

"I think it is really a breakthrough," said Wolfgang Wagner, professor of remote sensing at the Vienna University of Technology in Austria. He said that the satellite is the first to provide enough measurements over the right timescale to give detailed maps of soil moisture.

The maps have been produced as part of the SHARE project (Soil Moisture for Hydrometeorological Applications in the Southern African Development Community).

The SHARE project is part of ESA's TIGER initiative, which aims to assist African countries in managing water-related problems by using satellite data. The next stage of the initiative involves transferring leadership of the projects to African authorities.


Africa, July 30, 2007

Climate Change Center Foresees Longer Dryer Droughts

So what can we expect to see in the next 100 years? Unfortunately, we can expect to see many of the above trends continue or accelerate unless technological and social initiatives are carried out to curb emissions, provide more sustainable land and resource use, and increase economic security throughout the regions of the world. The IPCC used a variety of scenarios to project future impacts and trends. The scenarios differ in the assumed rate of population growth and expansion, rate of implementation of cleaner and more efficient energy, and levels of economic development. The scenarios also factor whether the loci of control for the implementation of the social, economic and environmental policies are global, regional, or local.

For example, a scenario with a peak in global population at mid-century and then an ensuing decline, with a global introduction of “clean and resource efficient technologies,” reduced material consumption and a focus on global solutions, resulted in a “best estimate” projected surface temperature change of 1.8 degrees by the last decade of this century. An alternative scenario that maintained the intensity of use of fossil fuels, with mid-century achievement of maximum global population and ensuing decline, rapid economic growth and increased social and cultural interaction and capacity building could result in a “best estimate” increase of 4.0 degrees by 2090.

Regardless of the specific scenario, IPCC projects that many of the observed trends are likely to continue. Specific projections related to drought include:

Decreased precipitation in tropical and subtropical land regions.

Increased hot nights, hot days and heat waves.

Increased evapotranspiration as a result of increased temperature and decreased precipitation.

Significant decrease in precipitation in the Sahel, Mediterranean, Southern Africa and Southern Asia.

Decline in mountain glaciers, snowpack and snow cover, particularly in the Northern Hemisphere.

Continued decrease in the total area of seasonally frozen ground.

A pole-ward movement of extratropical storm tracks resulting in continued changes in wind, temperature and precipitation patterns.

The IPCC’s projections demonstrate the need for actions to be taken on all levels to offset and mitigate the impacts of climate change. The panel projected more widespread and intense droughts in regions where the world is currently seeing high levels of population growth, economic development and social conflict, which will jeopardize food security, access to safe drinking water and economic stability for a high percentage of the world’s population.

End of excerpt.

Climate change is occurring in Africa as droughts are more sustained and severe than previously. This then means sustained famine and wars (as is ocurring in Darfur) as well as water shortages will continue to be part of life in this land particularly in Southern Africa, if people are not given the tools and education necessary to understand what is taking place and how to deal with it.

And not only will drought continue to change the landscape and way of life of millions of people, but changes in precipitation patterns brought about by erratic changes in sea surface temperature and melting glaciers will bring rains to those areas not accustomed to it, and a lack of precipitation in the very areas that need it most...the areas that depend on precipitation to grow food.

Water scarcity is not just the problem of lack of potable water. It is also a crisis that affects all we do from bathing, drinking, medical care, spiritual sustinence, and most importantly growing the food that sustains our bodies and minds.

Therefore, the satellite and radar technology now being enployed that can predict such disasters as floods and droughts while not being able to stop climate change and other factors leading to scarcity, drought, and its effects is an invaluable tool in working to save lives and perhaps in time be able to predict such occurrences further in advance in order to effect changes in agricultural areas that will best suit the needs of its people based on changing environmental conditions.

Nothing however, can replace the true good that can come from people having the knowledge mecessary to make informed and moral decisions regarding their use of water, and even though Africa is a continent being affected the most by this crisis, I still hold out hope in the humanity and goodwill of others that we can work together to solve this crisis in time. This radar technology is just one example.

Here is something else I support wholeheartedly:

Solar for Africa Waterpumps

Africa was made for solar power, and it is clean, safe, easy to install, and does not put out the amount of GHGS that other methods including nuclear do.

There are ways to solve this crisis. Together we can do it.

Main site:

Solar For Africa


Anonymous said…
Interesting post - one other thing to consider is to what extent this data is granular enough to be useful on a community-by-community level. For example, it is very difficult and expensive to drill for water in the Northern Region of Ghana because of a lack of hydrogeological data. It is almost twice as expensive per borehole in Ghana as it is in Nigeria, where such data exists due to the presence of the oil companies.